TY - JOUR
T1 - MCSED
T2 - A Flexible Spectral Energy Distribution Fitting Code and Its Application to z ∼ 2 Emission-line Galaxies
AU - Bowman, William P.
AU - Zeimann, Gregory R.
AU - Nagaraj, Gautam
AU - Ciardullo, Robin
AU - Gronwall, Caryl
AU - McCarron, Adam P.
AU - Weiss, Laurel H.
AU - Molina, Mallory
AU - Belles, Alexander
AU - Schneider, Donald P.
N1 - Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved..
PY - 2020/8/10
Y1 - 2020/8/10
N2 - We present MCSED, a new spectral energy distribution (SED) fitting code that mates flexible stellar evolution calculations with the Markov Chain Monte Carlo algorithms of the software package emcee. It takes broad-, intermediate-, and narrowband photometry, emission-line fluxes, and/or absorption-line spectral indices and returns probability distributions and covariance plots for all model parameters. It includes a variety of dust attenuation curves with parameters for varying the UV slopes and bump strengths, a prescription for continuum and polycyclic aromatic hydrocarbon emission from dust, models for continuum and line emission from ionized gas, options for fixed and variable stellar metallicity, and a selection of star formation rate (SFR) histories. The code is well suited for exploring parameter interdependencies in sets of galaxies with known redshifts for which there is multiband photometry and/or spectroscopy. We apply MCSED to a sample of ∼2000 1.90 < z < 2.35 galaxies in the five CANDELS fields that were selected via their strong [O iii] λ5007 emission, and we explore the systematic behavior of their SEDs. We find that the galaxies become redder with stellar mass due to both increasing internal attenuation and a greater population of older stars. The slope of the UV extinction curve also changes with stellar mass, and at least some galaxies exhibit an extinction excess at 2175 Å. Finally, we demonstrate that below M ≲ 109 M o˙, the shape of the star-forming galaxy main sequence is highly dependent on the galaxies' assumed SFR history, as calculations that assume a constant SFR produce stellar masses that are ∼1 dex smaller than those found using more realistic SFR histories.
AB - We present MCSED, a new spectral energy distribution (SED) fitting code that mates flexible stellar evolution calculations with the Markov Chain Monte Carlo algorithms of the software package emcee. It takes broad-, intermediate-, and narrowband photometry, emission-line fluxes, and/or absorption-line spectral indices and returns probability distributions and covariance plots for all model parameters. It includes a variety of dust attenuation curves with parameters for varying the UV slopes and bump strengths, a prescription for continuum and polycyclic aromatic hydrocarbon emission from dust, models for continuum and line emission from ionized gas, options for fixed and variable stellar metallicity, and a selection of star formation rate (SFR) histories. The code is well suited for exploring parameter interdependencies in sets of galaxies with known redshifts for which there is multiband photometry and/or spectroscopy. We apply MCSED to a sample of ∼2000 1.90 < z < 2.35 galaxies in the five CANDELS fields that were selected via their strong [O iii] λ5007 emission, and we explore the systematic behavior of their SEDs. We find that the galaxies become redder with stellar mass due to both increasing internal attenuation and a greater population of older stars. The slope of the UV extinction curve also changes with stellar mass, and at least some galaxies exhibit an extinction excess at 2175 Å. Finally, we demonstrate that below M ≲ 109 M o˙, the shape of the star-forming galaxy main sequence is highly dependent on the galaxies' assumed SFR history, as calculations that assume a constant SFR produce stellar masses that are ∼1 dex smaller than those found using more realistic SFR histories.
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U2 - 10.3847/1538-4357/ab9f3c
DO - 10.3847/1538-4357/ab9f3c
M3 - Article
AN - SCOPUS:85089568893
SN - 0004-637X
VL - 899
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 7
ER -